A general LED bulb is provided with a metallic heat dissipating member. The LED is disposed on the metallic heat dissipating member to realize effective heat dissipation. However, such LED bulb is bulky, and it is difficult to realize a whole view angle luminance. In order to overcome the above described shortcomings, a structure that replaces the LED disposed on the metallic heat dissipating member by LED filament is adopted, allowing the LED bulb to be light and handy, and capable of radiating in a whole view angle.
However, the conventional LED filament is damaged easily, and a high power, such as 8 watts, cannot be reached. When power is high, the temperature of the LED filament is higher, thus a luminance decrease occurs easily.